Many diseases may occur in locations of the body which are difficult to access without surgery or similarly invasive procedures. Thus it can be difficult to detect these diseases early, when a medical response may be most effective, and it can be difficult to monitor the progression of disease after it has been detected, especially if it requires screens which are expensive and/or invasive. In an attempt to respond to this challenge, many diagnostic tests in routine clinical use sample bodily fluids such as blood and urine which are easier to access, and analyze them for constituents reflective of the health status of the individual. In particular, the fluids may contain molecular or biological constituents which can be derived from multiple bodily locations (see, for example, Yahya et al., “The Clinical Utilization of Circulating Cell-Free DNA (CCFDNA) in Blood of Cancer Patients”, International Journal of Molecular Sciences, 2013; Leary et al., “Detection of Chromosomal Alterations in the Circulation of Cancer Patients with Whole-Genome Sequencing”, Science Translational Medicine, 2012; each of which is entirely incorporated herein by reference). However, when nucleic acids are detected in the body, distal from their source, there is no general method to know what the source tissue was. Thus if the quantity or other characteristic of the nucleic acids is indicative of disease, a physician may not know where the disease is located. In addition, because nucleic acids may have combined from many sources in the body, the sensitivity to detect a nucleic acid signal from any one part of the body may be limited by the presence of other nucleic acid signals from other parts of the body.